Stamping process for making sheet-metal articles



2 Sheets-Sheet P. SCHWARZ STAMPING PROCESS FOR MAKING SHEET METALARTICLES Filed Aug. 15, 1927 Dec. 17, 1929.

, "Q i Wk Patented Dec. I 17, 1929 PATEN T OFFICE PHILIP? SCHWABZ, F.IBARMEH, GERMANY STAMPING PROCESS FOR MAKING SHEET-METAL ARTICLESApplication filed August 13, 1927, Serial No.

The invention relates to a stamping process for making sheet metalarticles (e. g. metal buttons) having at least two stamped parts joinedtogether, and to such articles themselves. The invention deals thereforewith sheet metal objects which consist either of two stamped parts only,joined together or of two joined stamped parts in addition to othercomponents. An example of the latter case is a three or four part sheetmetal button consisting of two correspondingly formed sheet metal discsjoined together and one or two other parts, e. g. a spring discs clampedbetween the discs.

which the parts for stamping have been previously formed and accuratelysuperposed in rows or groups, are fed to a press and the two stampedparts to be joined are stamped out in one operation by a single punch;then by further travel of the punch and co-action of a counter-punchthey are preliminarily or finally joined. This enables an uncommonlysimple process and an equally simple apparatus to be employed, while atthe same time the accuracy of themanufactured article is improved andthe possibility of damage decreased.

The process is particularly simple if the stamping strips can simply belaid upon one another to bring all the previously formed parts forstamping on one strip accurately over the previously formed parts forstamping on the other, the two strips then being fed in common in thesame direction to the stamping apparatus.

The process and the article are further explained with reference to anexample illustrated in the accompanying drawing. The

40 case chosen is the making of a two part button with two apertures.

Figure 1 shows in longitudinal section on an enlarged scale thepreviously formed parts a and I) for stamping of a button, portions ofthestrips 0 and d also being shown. Figure'2 shows the stamped parts aand I) after preliminary joining and Figure 3 the stamped parts afterfinal joining that is, the complete button, which it will be understood59 could contain other components inside. Figs.

According to the invention, two strips on 212,737, and in Germany August18, 1926.

4 and 5 show diagrammatically the position of the superposed strips withrelation to the punch and die before and after the punch- 1ng operationrespectively; Fig. 6 shows a modified form of die; Figs. '7 and 8 showtwo positions of the press during the punching operation.

The case will first be considered Where the two parts after beingstamped out are to be joined preliminarily. The apparatus for this isshown in vertical section in different posltions in Figures i and 5. Allparts unnecessary for explanation of the invention are omitted. r

The strip 0 with the previously formed parts a and the strip 0! with thepreviously formed parts I) are closely superposed so that the parts a ofthe one strip lie directly over the parts I) of the other strip'insuitable position for' joining. The manner in which the parts arepreviously formed is no part of the present invention. The diameter Thestrips are then fed under a row or group of cutting punches f. The punchf has a d1ameter,'wh1ch exactly conforms with the of the'part a issmaller than that of the part b.

diameter of the curved part b, which is larger than the diameter of thepart a. The curvature at the lower end of thepunch f is greater than thecurvature of the part a. As the punch f descends, it presses at thecentral part of its curvature against the central part of the curvaturea without touching with its cutting edge the strip a. In this mannor thepart a will be pressed downwards and the material of the strip will bebent in on the edge of the curvature a. If the cutting edge of the punchf then touches the strip 0, the part a will be pressed into the part bin the form or shape as shown in Figure 2. The punch then cuts throughthe two strips so that the parts a and Z) are interposed as shown inFigure 2. advances further, it finally moves these in terposcd parts a7) into the space formed bV the rib Z" on the head-of the counter-punchi. The two parts a and 7) are now pressed firmly against each other, asshown in Figure 5, so that they are partially connected together. Thepreliminarily joined stamped When the punch f llIU parts are thenejected by an ejector m, while the punch f again rises and the strips 0,d are fed forward a predetermined distance. The preliminarily joinedstamped parts are then finally joined by other means in any suitable wayby bending over the outstanding edges. v

If this final joining is to be efiected in the same apparatus in asingle step, instead of the counter-punch 2', a counter-punch 1, Figure6, having a somewhat different form in vertical section is used.

This counter-punch n has in its upper face a cylindrical pocket intowhich the punch f presses the punched out parts after they have left thehollow die h. Here the inclined rim of the lower stamped part b is firstturned vertically up and even turned slightly inward, whereupon thesharp edge of the cutting punch f engages behind this rim and bends itover together with the rim of the upper stamped part a. The ejector mthen ejects the completed beaded button.

The, rods 8 shown in Figures 4, 5 and 6 are only guide rods which passthrough the holes in the parts a and b and into guide holes t in thepunch f and thus ensure that the two parts take the correct positionduring cutting and joining.

The process described results in the two stamped parts to be joinedoriginally having the same diameter. In order to permit joining bybending the edge of one part over that of the other, the latter mustfirst be reduced in diameter, which to a sufficient extent and withinthe operation of the process described can only be effected by bendingover the rim .to be enclosed (see Figures 1 to 3). Both stamped partstherefore have their edges headed over providing security againstrelative rotation of the two parts, which would interfere later insewing owing to the holes getting out of register. This kind of jointbetween the two stamped parts could be used in other manufacturingprocesses, and extends stamped parts to all articles consisting of twounited along their edges.

Naturally it is very important in the stamping process for the strips toremain exactly in correct relative position during feeding forward. Theusual feedingmeans are hardly suificient for this. Accordingtotheinvention in order to ensure the correct'ielative positions of thetwo strips during the. feed, the

feed is effected by at least one reciprocating carrier rod, whichalternately enters and leaves two superposed holes in the strips.

Figures 7 and8 show in vertical section the essential parts of thepunching apparatus and the essential parts of such a feed device, in

. two different positions.

It should first be explained that this feeding device is particularlysuitable for the simultaneous stamping'out of several successive doubleparts, that is for the multiple feed distance involved thereby, sinceboth strips are held in exactly the correct relative position during thefeed movement and in consequence there can be no objection to a longfeed stroke. In the drawing it is assumed that three successive doubleparts are to be stamped out simultaneously and the feed stroke istherefore three times the distance between adjacent buttons.

In these views, 0 and d are again the two superposed strips, which areintermittently fed forward in the direction of the arrow Z. Carrier rods2, 2, which are mounted on a slide 3 reciprocating in the feed deviceserve for this purpose. The slide is reciprocated by-an angle bar 4. Themeans for effecting this motion can be of any desired kind (say aneccentric and lever) and are not shown in the drawing. The rods 2, 2,each pass through two superposed holes in the strips 0, d. When, asassumed in the drawings, buttons with apertures are to be stamped, it issimplest to pass the rods 2 through the superposed sewing holes in thetwo strips. After the entry of the rods, the slide 3 is fed forward, sothat 'the rods move the strips forward, and the rods then leave theholes and return with the backwardly moved slide 3, in order once moreto enter holes in the strips located a stroke distance behind the first.

For further explanation reference is directed to Figure 8 which showsthe final position of the stamping tools. The three punches f have eachstamped an upper part and a lower part out of the strips 0, d and havepreliminarilyjoined them, as explained with reference to Figures 1 to 6.The preliminarily joined stamped parts rest on the slide 5, and afterthe punches have risen, are removed to receive a final joiningoperation.

On the press head 6, on which the punches fare mounted, plungers 7 areslidably carried under the action of springs 8. These plungers 7 whichpass similarly to the punches f through the stationary guide plate 9,press from above on the two strips 0, 03 while plungers 11 movingin thebed plate 10 under the action or springs 12, operate counter to theplungers 7. j

When the punches ,f begin to rise, at first the strips are held againstthe bed plate 10 by the upper plungers 7. Then theplu'ngers 11 pressthestrips 0, d upwards, while the plungers 7 also moveback, so that thestrips 0, d, are held suspended for a short time between the plungers 7and '11 and are then raised. During this time two pairs of holes in thestrips pass over the carrier rods 2 which take theposition shown inFigure 8-so that they pass through the holes. In the uppermost position,the punches f and the plungers 7 no longer contact with the strips.

The slide 3 with the rods 2 is now moved to 'v the left, so that ittakes the ositi'on shown in 0, (1 forward a stroke'length correspondingto three successive pairs of'parts and interthe pairs of part's'axiallmediate material;

press bed for pressing said strips upwards to reengIage said rod.

5. n apparatus for simultaneously stamping pairs of superposed partsprevlousl formed in sheet metal strips,

die in line with said punch and (1 means for turning the edges of bothof the low cutting a punch, a ho stamped out parts in the samedirection, said means being in line I with said punch and located on theopposite side of said die.

. In testimony the strips and if necessary" may. serve only for feedingpur o'ses,

What I c aim is:

-1. A stamping-process for making sheet metal articles comprising twostamped partsv joined at their edges, wh1ch consists in superposingtwostri'ps in which the parts to be punched have been previously formed,with aligned relative to. one another, thensimu taneously stampin with asingle punch a'pair'of superpose parts and then flanging the edges ofboth parts in thesame direction by further travel of the same punch andco action of a counterpunch.

2'. In apparatus for simultaneously stam ing pairs oi superposed partspreviousy formed in sheet metal strips, said parts eac being providedwith tures, being in superposed alignment, a feed device comprising afeed rod, means for reciprocating said rod longitudinally of the centerlines of the strips and means for causing said rod toenter and leave thesuper-- posed holes in 3. In apparatus for simultaneously stampsaidstrips.

ing pairs of superposed parts previously formed in sheet metal strips,said arts each being provided with a rt'ures, said apertures being insuperposed a inement, a press head a press bed, a feed device comprisinga fee rod adapted to engage said stn s, means for reciprocating said rodlongitu 'nally of the center lines of the strips, plungers on thepress'headdor pressin said strips downwards to disenga e said r0 andspring actuated plungers in t e press bed for pressing said stripsupwards to reengage said red.

In apparatus for simultaneously stamping pairs of superposed partspreviously formed in sheet metal strips, said parts each being providedwith apertures, said apertures being in superposed alinement, a pressapertures, said aper-- spring actuated head, a press bed, a feed devicecomprismga reciprocating bar reci rocating in a fixed gui e late, a feedro carried by said bar and a apted to engage said strips, springactuated plungers in the ress head for pressin said strips downwar todisengage said r and spring .actuated plungers 1n the whereof I aflix mysignature. PHILIPP SCHWARZ.

